is new hot hollywood treatment, it's called cupping. Jennifer aniston sporting marks from it. Linzie janis has more. It's a hot new thing for the stars. But it's been around for thousands of years. Talk about beauty marks. Normally flawless jennifer aniston turned heads when she showed up at her latest movie premier with an unusual access si. Large round welts all over her back. She doesn't have a ray skin disease. Her reps confirm the welts are the results of cupping. An ancient therapy. When the cup is placed upon the skin, the suction causes the blood vessels to dilate. Reporter: Stars like gwyneth paltrow, victoria beckham, david arquette, they're all big fans. The question is, does it work? We went to a spa in new york city to find out. This is the fire cupping. I'm taking an alcohol-soaked sotten ball, the fire consumes the oxygen and creates a vacuum. Reporter: Is it painful? Not at all. Reporter: It could help with fertility and well-being. When we see these marx, what is it likely they're being treated for? Organ systems, emotional, and physical at the same time. Reporter: Not all doctors say it works. It's thought to be safe. More studies need to be . Reporter: Most fully qualified accupuncture people are able to do it. I feel a little bit looser. It hurt. It pinched. Not sure I'm willing to sport big giant bruises. Was there anything physically, did you want to jump up and run, did you feel better? Could you run farther? Was there anything? It relieves tension in the same way maybe as a massage. But didn't leave bruises. It doesn't look good. It leaves marks. What are you thinking? Some say it makes them feel fabulous. Big bruises on your -- why? As sam champion continues to

This transcript has been automatically generated and may not be 100% accurate.

How to Get Your Favorite Red Carpet Look

Brad Goreski reveals how you can incorporate Hollywood's biggest trends into everyday looks.

{"id":19014736,"title":"Aniston, Paltrow Caught Up in 'Cupping' Craze","duration":"2:37","description":"Technique used for thousands of years is thought to relieve tension and improve circulation.","section":"GMA","mediaType":"Default"}